方程\( \ln x = ax \)\( \left( {a > 0} \right) \)只有一个实根（ ）
举一反三
- 5.下列函数中，在其定义域上有最大值和最小值的是（）。 A: $f(x)=\left\{ \begin{array}{*{35}{l}} \ln \left| x \right|,\ \ \ x\ne 0 \\ 0,\ \ \ \ \ \ \ \ x=0 \\ \end{array} \right.$ B: $f(x)=\ln \left( \left| x \right|+1 \right)\ x\in [-1,1]$ C: $f(x)=\ln \left| x \right|,\ \ \ x\in [-1,1]\backslash \{0\}$ D: $f(x)=\left\{ \begin{array}{*{35}{l}} \ln \left| x \right|,\ \ \ 0\lt |x|\lt 1 \\ 0,\ \ \ \ \ \ \ \ x=0 \\ \end{array} \right.$
- 1. $\int \frac{1}{x(1+x)} dx =$ A: \[\ln{(x)}-\ln{\left( x+1\right) }+C\] B: \[\ln{(x)}+\ln{\left( x+1\right) }+C\] C: \[x-\ln{\left( x+1\right) }+C\] D: \[-\ln{(x)}+\ln{\left( x+1\right) }+C\]
- \( \int {\sec xdx} \)=( )。 A: \( \ln \left| {\csc x + \tan x} \right| + C \) B: \( \ln \left| {\sec x + \cot x} \right| + C \) C: \( \ln \left| {\sec x + \tan x} \right| + C \) D: \( \ln \left| {\csc x + \cot x} \right| + C \)
- 函数$y = \ln x$，则${\left( {\ln x} \right)^{\left( n \right)}} = {\left( { - 1} \right)^{n - 1}}{{\left( {n - 1} \right)!} \over {{x^n}}}$。（ ）
- 函数\(z = {\left( {xy} \right)^x}\)的全微分为 A: \(dz = \left( { { {\left( {xy} \right)}^x} + \ln xy} \right)dx + x{\left( {xy} \right)^x}dy\) B: \(dz = \left( { { {\left( {xy} \right)}^x} + \ln xy} \right)dx + { { x { { \left( {xy} \right)}^x}} \over y}dy\) C: \(dz = {\left( {xy} \right)^x}\ln xydx + { { x { { \left( {xy} \right)}^x}} \over y}dy\) D: \(dz = {\left( {xy} \right)^x}\left( {1 + \ln xy} \right)dx + { { x { { \left( {xy} \right)}^x}} \over y}dy\)